This invention relates to liquid fertilizer solutions. It further relates to methods of preparing stable liquid fertilizers which contain nitrogen, phosphorus, iron and optionally sulfur.
Liquid fertilizers have been used for many years to provide plant nutrients in a form which can be assimilated by plants and can be easily and evenly distributed either into the soil or onto the plants themselves. A serious problem encountered in the preparation and use of liquid fertilizers is the difficulty of maintaining the complete solubility of all the components of the fertilizer solution. For reasons of economy and convenience, it is desirable to include as many plant nutrients as possible in a single fertilizer solution, but each additional nutrient must be introduced in a manner and from a source which does not disrupt the mutual solubility of all the components. The precipitation or crystallization of solids from the fertilizer solution causes plugging of storage and application equipment, resulting in uneven distribution of the liquid during application and costly maintenance of storage facilities, and also results in loss of the precipitated component of the fertilizer. Fertilizer solutions which appear on initial mixing to be stable sometimes gel after standing for a period of several weeks or months. A stable solution of several nutrients can sometimes be obtained in a fertilizer which is strongly acidic or basic, but this causes additional problems of equipment corrosion and the possibility of burning plant leaves if the pH of the solution is below about 5.0 or above about 8.0, or sometimes above 7.0 if free ammonia is present.
It is thus an object of this invention to provide a stabilized liquid fertilizer solution containing nitrogen, phosphorus, iron, and optionally sulfur.
It is another object of the invention to provide a stabilized liquid fertilizer which is not highly corrosive to metal surfaces.
It is a further object to provide a liquid fertilizer which can be applied either to the soil or directly to the plant.